Nanoscale grasping device, method for fabricating the same, and method for operating the same

ABSTRACT

A nanoscale grasping device comprising at least three electrostatically actuated grasping elements. The use of at least three elements, which together define a plane, allows an object to be grasped more accurately, more easily held, and more readily manipulated. The grasping elements preferably comprise conductive nanotubes which are grown at specific points on a substrate (e.g., directly on an electrode), using chemical vapor deposition (“CVD”) techniques, thereby allowing the grasping device to be manufactured with greater control. Different types of electrostatic forces may be used to open or close the grasping tool. Such attractive and repulsive forces can be created through the application of either a constant voltage or an oscillating voltage.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with Government support under contractDAAD17-01-C-0025 awarded by U.S. Army Robert Morris Acquisition CenterRMAC-Adelphi. The Government has certain rights in the invention.

FIELD OF THE INVENTION

This invention relates to nanoscale devices in general, and moreparticularly to a nanoscale grasping device particularly suited for thegrasping and manipulation of nanoscale objects, and to the fabricationand operation of the same.

BACKGROUND OF THE INVENTION

The techniques of atomic force microscopy (“AFM”) and scanning tunnelingmicroscopy (“STM”) are used to create three-dimensional topographic mapsof a surface, providing a level of detail that approaches, the case ofSTM, atomic resolution. These methods generally rely upon the use of asharp tip to sense the topography of a surface, including the positionof particles and objects on that surface, with tunneling current orforce data being used to provide the topographic information. These tipsare often etched from silicon. See, for example, U.S. Pat. No.5,242,541, issued Sep. 7, 1993 to Bayer et al. for METHOD OF PRODUCINGULTRAFINE SILICON TIPS FOR THE AFM/STM PROFILOMETRY.

It has also been recognized that nanofibers, such as carbon nanotubes,can make excellent tips for these imaging techniques. See, for example,Dai et al., “NANOTUBES AS NANOPROBES IN SCANNING PROBE MICROSCOPY”,Nature, Vol. 384, Nov. 14, 1996, Pages 147-150. One reason for theinterest in forming sensing tips out of carbon nanotubes is the highstiffness and aspect ratio common to carbon nanotubes. By way ofexample, the elastic moduli for carbon nanotubes are similar to thosefor diamond, as calculated and measured by various researchers,including Sinnott et al., “MECHANICAL PROPERTIES OF NANOTUBE FIBERS ANDCOMPOSITES DETERMINED FOM THEORETICAL CALCULATIONS AND SIMULATIONS”,Carbon, Vol. 36, Nos. 1-2, Pages 1-9, 1998; and Krishnan et al.,“YOUNG'S MODULUS OF SINGLE-WALLED NANOTUBES”, Physical Review B, Vol.58, No. 20, Nov. 15, 1998, Pages 14013-14019. Furthermore, in U.S. Pat.No. 5,824,470, issued Oct. 20, 1998 to Baldeschwieler et al. for METHODOF PREPARING PROBES FOR SENSING AND MANIPULATING MICROSCOPICENVIRONMENTS AND STRUCTURES, there is taught the chemical modificationof a silicon AFM tip to prepare a functionalized tip, which can includea nanotube.

The aforementioned sensing tips are primarily designed to function asinterrogation tools, and are generally poorly suited to physicallymanipulate objects. With the aforementioned sensing tips, objectmanipulation is generally limited to either pressing an object against asurface or pushing the object across a surface. The aforementionedsensing tips generally lack the ability to pick up, translate or depositan object elsewhere. If these tips could perform such grasping,translating and deposition functions, a large variety of differentpatterns, structures, circuits and devices could be assembled withmicroscale, nanoscale or near atomic resolution.

To perform these more sophisticated manipulation functions, a graspingtool is generally required. In this respect a two element, tweezer-typegrasping tool is described in Kim et al., “NANOTUBE NANOTWEEZERS”,Science, Dec. 10, 1999, v286, i5447, p2198. More particularly, Kim etal. teach the construction of a two element tweezer using two nanotubes.One end of each nanotube is adhesively bonded to an electrodedmicropipette, with the other end of each nanotube remaining free. Apre-determined DC voltage differential selectively applied to the twoelements causes electrostatic attraction of the two free tips, therebycausing them to close down on an object.

However, the two element tweezer of Kim et al. can be somewhat unstableand difficult to control, can be relatively difficult to construct, andprovides minimal operating control.

More particularly, the two elements of the Kim et al. tweezer togetherdefine only a line contact, which is inherently unstable and difficultto control, particularly in a nanoscale device.

In addition, the Kim et al. tweezer is constructed by selectivelyadhering individual nanotubes to electroded micropipettes. This is, atbest, a difficult and inexact procedure, and makes tweezer fabricationproblematic inasmuch as alignment, nanotube length and the point ofattachment cannot be directly controlled.

Furthermore, Kim et al. used a simple, pre-determined DC voltage tocreate the attractive and repulsive forces used to close and open thetweezers. This provides minimal operating control.

SUMMARY OF THE INVENTION

As a result, one object of the present invention is to provide animproved nanoscale grasping device which is relatively stable and easyto control.

Another object of the present invention is to provide an improvednanoscale grasping device which is relatively easy to construct.

And another object of the present invention is to provide an improvednanoscale grasping device which has increased operating control.

Still another object of the present invention is to provide an improvednanoscale grasping device which has an improved method of operation.

These and other objects of the present invention are addressed by theprovision and use of a novel nanoscale grasping device comprising atleast three electrostatically actuated grasping elements. In accordancewith the present invention, it has been discovered that the use of atleast three elements, which together define a plane, allows an object tobe grasped more accurately, more easily held in a defined location ororientation, and more readily manipulated.

In one preferred form of the invention, the grasping elements compriseconductive nanotubes which are grown at specific points on a substrate(e.g., directly on an electrode), using chemical vapor deposition(“CVD”) techniques, thereby allowing the grasping device to bemanufactured with greater control.

And in one preferred form of the invention, different types ofelectrostatic forces may be used to open or close the grasping tool.More particularly, in accordance with the present invention, suchattractive and repulsive forces can be created through the applicationof either a constant voltage or an oscillating voltage.

Furthermore, it has been discovered that by changing the phase of theoscillating voltage on each grasping element, the attractive andrepulsive forces between multiple grasping elements can be controlled soas to cause the opening or closing of the grasping elements.

Additionally, in accordance with the present invention, it has beendiscovered that the magnitude of the DC or oscillating voltage can beadjusted so as to alter the attractive forces created between thegrasping elements.

And in the case of the oscillating voltage, the frequency or speed atwhich the phases transform can be altered so as to adjust the grippingaction between the various grasping elements. Additionally, thefrequency or speed at which the phases transform can be altered so as tocancel or enhance resonant thermal or mechanical vibration of thenanotubes.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute partof the specification, schematically illustrate preferred embodiments ofthe invention and, together with the general description given above andthe detailed description of the preferred embodiments given below, serveto explain the principles of the invention.

FIG. 1A is a schematic representation of a three element nanoscalegrasping device, fabricated on a substrate with electrodes for voltageapplication. An object which is to be grasped sits below on a surface.

FIG. 1B is a schematic representation of the same nanoscale graspingdevice holding an object after a voltage has been applied to thegrasping elements, causing them to close around the object.

FIG. 2A a schematic representation of the forces exerted on a threeelement nanoscale grasping device when a static voltage, either positive(+), negative (−), positive (+) or otherwise, is applied to the graspingdevice. An object in the center will be grasped by the device.

FIG. 2B is a schematic representation of the relative positions of thegrasping elements after the voltage has been applied. It should be notedthat this grasping mechanism is well suited to grasping oblong orirregular shaped objects.

FIG. 3 consists of a set of four schematic representations (FIGS. 3A,3B, 3C and 3D) of an oscillating voltage applied to the graspingelements and the electrostatic forces created between the graspingelements at different points in the cycle. When the time average forcesare calculated, the net effect is an attractive force between the threegrasping elements. If the phase rotation speed is slow, the individualmotions of the grasping elements may be observed, but as the phaserotation speed is increased, the time average phenomenon dominates theoverall effect.

FIG. 3A is a schematic representation of a three phase alternatingvoltage that is applied to each of the three grasping elements, 10, 15and 20, respectively, producing a time averaged net attraction andcorresponding closure of the elements about the center. V1 representsthe voltage on grasping element 10, and is represented by a solid line.V2, the voltage on grasping element 15, is represented by a short dashedline. V3, the voltage on grasping element 20, is represented by a longdashed line.

FIG. 3B is a schematic representation of the three grasping elements atone point in the voltage cycle, where the grasping element 10 is at itsmaximum positive voltage V1. The grasping element 15 and graspingelement 20 are both at negative potentials, V2 and V3 respectively, andare equal, although not at their maximum negative potential. Anelectrostatic attractive force exists between grasping elements 10 and15, and between grasping elements 10 and 20, but the interaction betweenthe grasping elements 15 and 20 is repulsive.

FIG. 3C is a schematic representation of the three grasping elements atanother point in the voltage cycle, where the voltage V1 on graspingelement 10 is positive but reduced from its maximum positive voltage.Grasping element 15 at this point has a zero voltage V2. Graspingelement 20 is approaching its maximum negative voltage V3. A strongattractive force exists between grasping elements 10 and 20. Dependingon the amount of polarization (charge separation) at the tip of graspingelement 15, there will be some attractive force between all three of theelements.

FIG. 3D is a schematic representation of the three grasping elements ata later point in the voltage cycle, where the voltage V1 on graspingelement 10 is equivalent to the voltage V2 on grasping element 15, andgrasping element 20 has acquired its full negative potential V3. Thesituation is symmetric and similar to the condition shown in FIG. 3B,although the signs are reversed. An attractive force exists betweengrasping elements 15 and 20, and also between grasping elements 15 and20, but a repulsive force is established between grasping elements 10and 15.

FIG. 4A is a schematic representation of a nanoscale grasping devicecomprising four grasping elements 10, 15, 20 and 45, fabricated on asubstrate 25, with electrodes 30 for voltage application. An object 35sits below the grasping device on a surface 40.

FIG. 4B is a schematic representation of the same nanoscale graspingdevice holding the object 35 after a voltage has been applied tograsping elements 10, 15, 20 and 45, causing them to close around theobject.

FIG. 5A is a schematic representation of the grasping elements 10, 15,20 and 45 before any voltage is applied. An object 35 is located betweenthe elements.

FIG. 5B is a schematic representation of the same nanoscale graspingdevice after a steady state voltage is applied to the electrodes. Inthis figure, grasping elements 10 and 20 share the same voltage, whichis opposite to the voltage applied to grasping elements 15 and 45.Arrows indicate the resulting electrostatic attractive and repulsiveforces. The weaker diagonal repulsive forces will be overcome by theorthogonal attractive forces, resulting in a net attractive force.

FIG. 5C is a schematic representation of the same nanoscale graspingdevice after the voltage has been applied and the effects of theelectrostatic attraction have caused the grasping elements to cometogether, resulting in a compressive force on the object 35 between theelements.

FIG. 6A represents an oscillating voltage applied to a four elementarray and the forces created between the grasping elements at differentpoints in the cycle. When the time average forces are calculated, thenet effect is an attractive force between the grasping elements. Again,if the phase rotation speed is slow, the individual motions of theelements may be observed, but as the phase rotation speed is increased,the time average phenomenon dominates the overall effect.

FIG. 6B is a schematic representation of the four grasping elements atone point in the voltage cycle, where grasping element 10 is at itsmaximum positive voltage V1, grasping element 45 is at its maximumnegative potential V4, and therefore an attractive force exists betweengrasping elements 10 and 45. Grasping elements 15 (V2) and 20 (V3) areat zero potential, but to the extent that they will polarize, there maybe an attractive force between all of the elements. Arrows indicate theattractive force between grasping elements 10 and 45.

FIG. 6C is a schematic representation of the grasping four elements at alater point in the voltage cycle; here, grasping elements 10 and 20 areat the same positive voltage, while grasping elements 15 and 45 are atthe same negative voltage. An attractive force exists between graspingelements 10 and 45, and between grasping elements 10 and 15, and betweengrasping elements 20 and 45, and between grasping elements 15 and 20;while a repulsive force is felt between grasping elements 10 and 20, andbetween grasping elements 15 and 45. Ar rows indicate the attractive andrepulsive forces. The net result is compression of the tips towards eachother.

FIG. 6D is a schematic representation of the four grasping elements at alater point in the voltage cycle; here, grasping elements 10 and 45 areat zero volt age, while grasping elements 15 and 20 have reachedopposite maximum voltages. An attractive force exists between graspingelements 15 and 20, and the overall effect is equivalent to that of FIG.6B.

FIG. 6E is a schematic representation of the grasping four elements at alater point in the voltage cycle; here, grasping elements 10 and 15 areat the same negative voltage, while grasping elements 20 and 45 are atthe same positive voltage. An attractive force exists between graspingelements 10 and 45, and between grasping elements 10 and 20, and betweengrasping elements 15 and 20, and between grasping elements 15 and 45;while a repulsive force is felt between grasping elements 20 and 45, andbetween grasping elements 10 and 15. Arrows indicate the attractive andrepulsive forces. The net result is compression of the tips towards eachother.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to a nanoscale grasping device, amethod of fabricating the same, and operation of the same.

In one preferred form of the present invention, a substrate is patternedwith a number of electrodes, and a catalyst particle is deposited atopeach electrode. A nanotube is then grown from each catalyst particle,resulting in a nanotube attached at one end to a substrate electrode.The application of a voltage on the electrodes creates electrostaticattractive and repulsive forces between the tips of adjacent nanotubes,resulting in a grasping action between the nanotubes.

Referring first to FIG. 1A, there is shown a three element nanoscalegrasping device 5 comprising three grasping elements 10, 15 and 20fabricated on a substrate 25. Substrate 25 may be an insulator such asglass, quartz, alumina and the like, or a semiconductor such as siliconor germanium and the like. Any substrate that can support deposition ofelectrodes 30 and grasping elements 10, 15 and 20 will suffice.Substrate 25 may stand alone or be mounted to another structure (notshown) comprising circuits and/or electrical components.

Electrodes 30 can be produced lithographically, patterned usingphotoresists and masks, or by other techniques such as electron beamlithography, dip pen lithography, lithographically induced self assembly(“LISA”), and self assembled monolayers to mask off specific areas. Oncepatterned, electrodes 30 can be deposited on the unmasked areas.Electrodes 30 are commonly produced from conductive metals such as gold,silver, copper, chromium, aluminum, titanium, nickel, and their alloys,or from conductive oxides such as indium tin oxide (“ITO”). Evaporationand sputter deposition are commonly used methods to deposit metals.Electrodes 30 provide the electrical contact between grasping elements10, 15 and 20, and their respective voltage sources.

A subsequent patterning and deposition process can be used to create acatalytic deposit (not shown) atop electrodes 30. Again, the samepatterning and deposition processes are applicable to the production ofthe catalytic deposit. Catalytic materials include, but are not limitedto, iron, cobalt, nickel, and their oxides and alloys. Additives to thecatalyst are known, and these include yttrium, molybdenum, magnesium,calcium and titanium, and their oxides and alloys. These catalyticdeposits can be produced advantageously by electron beam lithography, asthis method is suited to produce small features. These catalystmaterials are known to catalyze the synthesis of carbon nanotubes, whichgrow attached to the electrode at one end, and extend into the freespace above the electrode at the other. These carbon nanotubes form thegrasping elements 10, 15 and 20. If the catalytic deposit is small,between about 20 and 150 nm in diameter, a single nanotube with an outerdiameter nearly matching the deposit can be grown. For deposits largerthan about 150 nm in diameter, multiple nanotubes are frequentlynucleated. However, variations in CVD growth conditions can alter thistransition point. The thickness of the catalytic deposit can also bevaried, and impacts the morphology of the nanotube.

The synthesis of the carbon nanotube elements from the catalyticdeposits requires the introduction of the sample to a chemical vapordeposition (CVD) system. Many different processes are known in the artto create aligned nanotube growth, each with its own advantages anddrawbacks.

One set of conditions that is well suited to this fabrication occurs inan environment where the temperature, pressure, gas composition andelectric field are controlled. It is advantageous to control thetemperature to between about 400 and about 900 degrees C., mostfavorably to near 700 degrees C.; the pressure to between about 0.1 andabout 50 Torr, more favorably to about 1 to about 20 Torr; and the DCapplied electric field strength to between about 200 volts percentimeter (V/cm) and about 500 V/cm, preferably near 300 V/cm. Thecomposition of the gas flowed through the CVD chamber is between about5% and about 50% acetylene, ethylene, methane, toluene or other carboncontaining gas, with the balance being ammonia, nitrogen, hydrogen, orother non-carbon bearing gas. A preferred gas composition is achievedwith about a 4:1 flow rate ratio between ammonia and the acetylene,using nickel catalyst deposits on a silicon wafer with chromiumelectrode contacts. These conditions favor nanotube nucleation andgrowth, and are maintained until the nanotubes have grown to the desiredlength. Typical process times do not exceed about one hour at theseconditions. Nanotubes can be grown from about 20 to about 150 nm indiameter, and up to about 40 microns in length under these conditions.Smaller nanotubes are produced by smaller diameter catalytic deposits ofother metals and can be more favorably grown at other conditions, as iswell known in the art.

As the nanotube's aspect ratio (i.e., height to diameter) increasesabove about 1000:1, there is decreased alignment as the tips begin toflop over. Therefore, there is a maximum length for the nanotube to begrown to retain its structural rigidity. In practice, it has been foundthat about 20 microns is a practical length for the favored embodiment.Additionally, it has been found that the nanotube tip morphology can bechanged. Round, flat and pointed tips are created by variations inprocess conditions. After growth, the catalytic deposits will havenucleated and grown aligned carbon nanotube elements 10, 15 and 20 atopelectrodes 30, resulting in the grasping device shown in FIG. 1A or inanother, similar device as defined by the lithographic patterning of theelectrode and catalyst.

Electrical stimuli (such as electrostatic charges) can be applied tonanotubes, if the nanotubes are conductive. The electrical conductivityof carbon nanotubes has been measured, and found to be dependent uponthe individual nanotube geometry. Carbon nanotubes are often conductive,with a resistivity of approximately 10⁻⁴ ohm cm. See, for example, A.Thess et al., “CRYSTALLINE ROPES OF METALLIC CARBON NANOTUBES”, Science,273, 483-487 (Jul. 26, 1996).

Still referring to FIG. 1A, nanoscale grasping device 5 is positionedabove an object 35 on a surface 40. Now referring to FIG. 1B, a voltageV1 is applied to grasping element 10 through the correspondingelectrode. Voltages V2 and V3 are applied to the other electrodes,respectively, whereby they will be applied to grasping elements 15 and20, respectively. When the applied voltages cause electrostaticattraction, the tips of grasping elements 10, 15 and 20 approach oneanother, thereby trapping object 35 between the tips, as portrayed inFIG. 1B. Application of further voltage may bend or compress the objectwithin the grasping device. Upon removal of the voltages, the tips maystay closed, if Van der Waals forces are sufficient to overcome therestoring force of the strained grasping elements. In this case, theapplication of the same voltage to all three grasping elements willcause electrostatic repulsion, and open the closed grasping device,thereby releasing the object. If the Van der Waals forces are weakcompared to the restoring force of the elements, the grasping tool willopen spontaneously upon removal of the voltages, releasing the object.The application of the voltages V1, V2 and V3 can be provided directlyby a phased power supply (not shown) or switched by a CPU to applycomplex waveforms to the elements.

Significantly, by forming the nanoscale grasping device with at leastthree elements, which together define a plane, the target object may begrasped more accurately, more easily held in a defined location ororientation, and more readily manipulated.

Referring next to FIGS. 2A and 2B, the grasping of a particle can beaccomplished using a static applied voltage. Grasping element 10 ischarged to voltage V1. Grasping elements 15 and 20 are charged tovoltages V2 and V3, respectively, which are both equal and opposite toV1. Object 35, located between the three grasping elements, is graspeddue to the electrostatic attraction between grasping elements 10 and 15and between grasping elements 10 and 20. The repulsion between elements15 and 20 widens the span of the grasping area.

Referring next to FIG. 3A, the voltages V1, V2 and V3 may vary in aperiodic fashion with time. Periodically varying potentials may include,for example, sinusoidal, squarewave and sawtooth waveforms, and may bebiased above zero voltage. For convenience, a sinusoidal waveform with aconstant baseline amplitude is shown in FIG. 3A. The phase of thepotential on each grasping element lags in this example by 120 degrees.FIGS. 3B, 3C and 3D are representations of the forces created by theapplication of the oscillating voltages on the elements, as seen lookingdown upon grasping elements 10, 15 and 20. At different points in thecycle, each element undergoes a time varying attraction or repulsion tothe other elements. At the portions of the cycle indicated by FIGS. 3Band 3D, there is an effect equivalent to the steady state case, shown inFIG. 2A. Forces are indicated by arrows. At the intermediate pointportrayed in FIG. 3C, the grasping element at zero potential becomespolarized, and the effect is a strong compressive force between the twocharged grasping elements, and a weaker compressive force (indicated bydashed arrows) between the polarized element and the charged elements.When the time average forces are considered, there is an overallattractive force between the three elements.

FIGS. 4A and 4B are, like FIGS. 1A and 1B, both schematicrepresentations of a multiple element grasping device, fabricated on asubstrate with electrodes for voltage application. In FIGS. 4A and 4B,the grasping has been constructed with four grasping elements. After avoltage has been applied to the grasping elements, the elements graspthe object as shown in FIG. 4B.

This tool has some distinct features that should be noted. FIG. 5A showsthe rest positions of the four grasping elements 10, 15, 20 and 45surrounding an object 35. A steady state voltage is applied to elements15 and 45, and an opposing voltage is applied to elements 10 and 20. Thevoltage induces electrostatic attractive and repulsive forces at thetips, which are portrayed in FIG. 5B. Weaker diagonal repulsive forceswill be overcome by the orthogonal attractive forces, resulting a netattractive force, thereby grasping object 35 between the graspingelements, as shown in FIG. 5C. The four element array can be actuated ineither a corner-to-corner mode or a side-to-side pattern, with differentresulting grasping action.

Alternatively, the four grasping elements may be driven by oscillatingpotentials, in the manner described about for the three element graspingdevice. For the four element device, FIG. 6A schematically representsthe oscillating voltage. FIGS. 6B, 6C, 6D and 6E represent the elementtips and the forces created between them at different points in thecycle. Again, when the time average forces are calculated, the net is anattractive force between the grasping elements.

It is also important to note that the electrical properties of theobject between the elements can be measured using the four point tool.It may be advantageous to make the measurements at the point of zerovoltage in one pair of electrodes.

The voltage required to actuate the elements is a function of nanotubestiffness, which is in turn a function of nanotube length and diameter.The voltage required to bring the elements together is also a functionof the contact area, or size of the nanotube.

The objects that can be grasped depend upon the spacing between thenanotubes. An object somewhat larger can be accommodated by applying acommon potential to all of the grasping elements, which will drive themapart.

The ability to control the voltage applied to the tips allows thegripping strength to be altered. The gripping strength will depend uponthe voltage-induced strain in the nanotubes. If a sufficiently highvoltage was applied to the grasping elements, the object may be strainedor sheared into pieces.

The multiple element grasping device can also be used as a standard AFMtip, to locate objects on a surface, either when closed, thereby forminga single tip, or when open, thereby forming a multi-tip AFM.

ALTERNATIVE EMBODIMENTS

The oscillating voltages may be applied in a manner such that a torqueis placed on the object within the gripping elements. This may be usedto rotate the object.

It should also be appreciated that a field of such elements could beaddressed in a transverse wave pattern to produce a repeating pattern ofwaves across the surface. Such motion could impart surface motioncapabilities, or serve as a form of micro-locomotion.

1. A nanoscale grasping device for the manipulation of microscopicobjects, said nanoscale grasping device comprising a substrate, at leastthree elongate electrically conductive grasping elements each havingfirst and second opposite ends, with said first ends attached to saidsubstrate and making electrical connections with an alternating currentsource and said second ends projecting outwardly away from saidsubstrate, whereby said second ends are free to be attracted or repelledrelative to one another in response to application of alternatingcurrent to said elements.
 2. The nanoscale grasping device of claim 1wherein said at least three grasping elements are nanofibers.
 3. Thenanoscale grasping device of claim 1 wherein at least one of saidgrasping elements comprises a carbon nanotube.
 4. The nanoscale graspingdevice of claim 3 wherein said carbon nanotube is integral with one ofsaid electrodes.
 5. The nanoscale grasping device of claim 2 wherein atleast one of said grasping elements is configured to bind specificmolecules thereto.
 6. The nanoscale grasping device of claim 2 whereinat least one of said grasping elements is configured to bind particlesthereto.
 7. The nanoscale grasping device of claim 1 comprising at leastfour grasping elements having their first ends making electricalconnections with said alternating current source, whereby said secondends of said grasping elements can be moved toward and away from oneanother by electrostatic forces in response to alternating currentapplied to said at least four grasping elements.
 8. The nanoscalegrasping device of claim 7 consisting of four grasping elements, withsaid four grasping elements arranged in a rectangular pattern on saidsubstrate.
 9. The nanoscale grasping device of claim 7 wherein saidalternating current source is configured to apply an oscillating voltageto at least one of said grasping elements.
 10. The nanoscale graspingdevice of claim 7 further including an oscillating voltage applied to atleast first and second ones of said grasping elements, with theoscillating voltage applied to said first one of said grasping elementsin phase with the oscillating voltage applied to said second one ofgrasping elements.
 11. The nanoscale grasping device of claim 7, whereinsaid alternating current source is configured to apply an oscillatingvoltage to first and second ones of said grasping elements via saidelectrodes, wherein the oscillating voltage applied to said first one ofsaid grasping elements is substantially out of phase with theoscillating voltage applied to said second one of the said graspingelements.
 12. The nanoscale grasping device of claim 1 wherein saidalternating current source is configured to apply voltages to saidelements so as to cancel or enhance resonant vibration of said graspingelements.
 13. The nanoscale grasping device of claim 1 comprising threeof said grasping elements, and wherein said alternating current sourceis configured to apply an oscillating voltage at each of said threeelements with the voltage at each element substantially 120 degrees outof phase with the voltage at the other elements.
 14. The nanoscalegrasping device of claim 1 wherein said grasping tool comprises fourgrasping elements, and further wherein said alternating current sourceis configured to apply a steady state voltage at two neighboringelectrodes and different voltages at the other two electrodes.
 15. Thenanoscale grasping device of claim 7 wherein said grasping toolcomprises four grasping elements, and further wherein said alternatingcurrent source is configured to apply an oscillating voltage to each ofsaid grasping elements, with said oscillating voltage applied to each ofsaid grasping elements substantially 90 degrees out of phase with oneanother.
 16. The nanoscale grasping device of claim 1, wherein at leastone of said grasping elements is configured for use as a probe in atomicforce microscopy and scanning probe microscopy techniques.
 17. Thenanoscale grasping device of claim 1, wherein at least one of saidgrasping elements is configured for use in performing electrical andmechanical analysis of the sample.
 18. The nanoscale grasping deviceaccording to claim 1 wherein said alternating current source isconfigured to apply oscillating voltages to said grasping elements so asto cancel or enhance resonant vibration thereof.
 19. The nanoscalegrasping device comprising a substrate, three elongate, fibrous,electrically conductive grasping elements projecting outwardly away fromsaid substrate, and three electrodes on said substrate configured toprovide an oscillating voltage to each of said three elongate, fibrous,electrically conductive grasping elements, whereby to cause the freeends of said electrically conducting grasping elements to be attractedor repelled relative to one another.
 20. The nanoscale grasping deviceaccording to claim 19 wherein said grasping elements are carbonnanotubes.
 21. The nanoscale grasping device of claim 20 wherein saidcarbon nanotubes have a diameter in the range of about 20 to about 150nm and a length in the range of about 20 to about 40 nm.
 22. Thenanoscale grasping device comprising of a substrate, at least threefibrous electrically conductive grasping elements having first ends andsecond ends, the first ends in electrical connection with separateelectrodes on the substrate, and the second ends projecting outwardlyfrom the substrate, and an alternating current source in electricalconnection with the separate electrodes on the substrate, each of saidgrasping elements separated from one another by a gap, whereby saidsecond ends are configured to move in a direction to increase ordecrease said gaps as a function of electrostatic attraction caused byalternating current applied to said electrodes.
 23. The nanoscalegrasping device of claim 1 wherein said substrate and said graspingelements form a polygon with said second ends of said at least threeelongate electrically conductive grasping elements positioned togetherwith one another.
 24. The nanoscale grasping device of claim 1 whereinsaid alternating current source is configured to apply an oscillatingvoltage to one of said at least three elongate electrically conductivegrasping elements, and further wherein said alternating current sourceis configured to apply another voltage to the other ones of said atleast three elongate electrically conductive grasping elements.